A rotary variable resistor with switch is characterized by having two mechanisms, that is, the variable resistance mechanism for varying the resistance value, and the switch mechanism for electric contact and non-contact by on/off operation of the switch.
In a conventional rotary variable resistor with switch, the variable resistance mechanism and the switch mechanism are stacked in two layers, one atop the other, and the switch mechanism includes a spring (torsion coil spring, etc.) and a metal piece used as a contact. Hence, in general, due to the increased number of parts, the size of a conventional rotary variable resistor is somewhat larger than that of an ordinary rotary variable resistor (VR) having only a variable resistance mechanism. In addition, the assembly process is more complicated, and the manufacturing cost higher, than that of an ordinary rotary variable resistor (VR).
In the past, it has been very difficult to add a switch mechanism to a conventional ultrathin rotary variable resistor, as shown in FIG. 13, without both an increase in thickness and cost. Prior attempts to add a switch to a VR have involved attempting to fit a switch mechanism onto the back side of the ultrathin VR, but the complicated, more costly assembly procedure has always resulted in an increase in thickness.
Therefore, a simple switch mechanism applicable to a new ultrathin rotary variable resistor, having only a small in increase in the cost, number of parts and complexity of assembly process, has been desired. In addition, it is important that said switch mechanism have a knob which can be held and felt securely by a user and, when the switch is turned on or off, a clicking sound should be clearly discernible.
New small, thin electronic appliances, such as card radios, portable stereo cassette recorders, and electronic pulse massager's require ultrathin rotary variable resistors of less than 2 mm in thickness. Recently there is a mounting demand for adding a switch to such ultrathin rotary variable resistors, but at present, such ultrathin rotary variable resistors with a switch, as described above, have been unavailable.